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The "Mental Rotation" Experiment

When tutorials refer to the "Mental Rotation" experiment, retend the data were collcted from a variant of the research reported by

Shepard, R. N. & Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171, 701-703.

Research Question :

Does it take longer to recognize two stimuli as being the same if one of the pair is turned or rotated with respect to the other?

Research Task:

Subject sees two figures on a computer screen. If the two figures are the same, then press the "S" key. Press the "D" key is they are different


The proper key to press here is the "D" key because one cannot be rotated clockwise or counter-clockwise to match the other. To match one would have to be "flipped" like a pancake.

Procedure: After instructions and working on a practice task, the subject sees pairs of stimuli on a computer screen. The two stimuli may be the same or different figures. The two figures are either oriented the same (0°) or one figure is rotated 45° or 90°. The subject is to press the "S" key if the figures are the same figure, discounting rotation That is, if one figure can be "picked up off the computer screen and turned to exactly match the other figure without flipping it, the subject is to report they are the same figure. If they are different figures or requires flipping the "D" key should be pressed. The subject is to respond as quickly as they can on each trial. There are 200 trials (100 "S" and 100 "D" trials).
Independent Variable (IV):

The rotational difference of the two figures (0°, 45°, 90°).

Dependent Variable (DV):

How long it takes to correctly press the "S" key. Only 1 number is used from each subject--the average time it took to respond "S" when the figures are the same.

[This analysis does not consider the conditions when the figures were different or when the subject presses the "D" key when the "S" key was correct.]

Experiment Design:

Completely Randomized. That is, each subject sees figure pairs of only ONE rotation. That is, each subject experiences only 1 level of the independent variable.

The Data Set
0° Rotation
45° Rotation
90° Rotation
Subject 1*
Subject 2
Subject 3
Subject 4
Subject 5
Subject 6
Subject 7
Subject 8
Subject 9
Subject 10
Subject 11
Subject 12
Subject 13
Subject 14
Subject 15

* Subject numbers are for identification purposes only. The number does not indicate the order in which data was collected.

©1997 - 2006 by Burrton Woodruff. All rights reserved. Last modified Tue, Sep 26, 2006